White mold
2 host plants
Magnolia develops white mold when grown in poorly drained soils or with overhead irrigation. Plant in well-drained soil, avoid overhead watering, and space plants for air circulation. Remove and destroy infected plants. Do not compost diseased material. These preventive practices are your best defense.
Remove affected material as you find it and clean up any fallen debris where white mold spores can overwinter. Improve air circulation around susceptible plants through selective pruning. Avoid overhead irrigation during vulnerable growth periods. If the problem is persistent, your local Extension office can recommend current fungicide or bactericide options for your specific situation.